Ishaan was assigned problems 25 through 51 for homework last week. If Ishaan did all of the problems he was assigned, how many problems did he do?
Solution: Instead of counting problems 25 through 51, we can subtract 24 from each number so we instead consider problems 1 through 27. We see that Ishaan did 27 problems. Notice that he did 27 and not 26 problems.